In recent years, as one of treatment methods of ophthalmic diseases such as cataract that abnormalities in eye lenses, a method comprising steps of removing eye lens contents from a capsular sac and inserting an artificially produced intraocular lens into a space thereof have been increasingly used.
In the case of the insertion of the intraocular lens, the intraocular lens may give a clear sight to patients by replacing the natural eye lens. However, regardless of many advantages of the intraocular lens the intraocular lens has problems that a capsular sac which the intraocular lens is inserted into contracts after the insertion of the intraocular lens.
Accordingly, a new method has been increasingly used, comprising steps of inserting a capsular tension ring into an equatorial region of a capsular sac prior to the insertion of the intraocular lens and fixing the intraocular lens in the capsular tension ring.
The capsular tension ring, which is referred to as an open or a closed ring formations, is effective in partially relieving contraction of the capsular sac and fixing the intraocular lens.
In order to use the capsular tension ring more effectively, there have been recently studies to develop a structure for easily inserting the capsular tension ring, a structure for preventing a posterior capsule opacity, etc.
However, a serious problem in conventional intraocular lens implantation is that an anterior capsule and a posterior capsule of the capsular sac adhere to each other after the surgical operation, which leads to the loss of inherent function of contrail a thickness of an eye lens by relaxing and contracting Zonule of Zinn. That is, the problem is that a patient cannot be ensured sight through active three-dimensional movement of an intraocular lens in the direction of objects to be seen, but merely ensures a passive sight according to the predetermined power of an intraocular lens. Hereinafter, the problem will be described in detail with reference to the accompanying drawings, FIGS. 1 to 4.
FIG. 1 is a cross-sectional view showing a human eyeball and FIG. 2 is a cross-sectional view showing a structure of a natural eye lens. Referring to FIGS. 1 to 4, a cornea 1 is a transparent avascular tissue disposed in the outermost region of the eye and protects the eyeball. Also, the cornea serves to reflect the light together with the eye lens. An iris 2 functions as the iris of a camera by adjusting the intensity of the light entering the eye. In addition, a pupil 3 is a hole in the center of the iris 2, and adjusts the intensity of the light entering a retina 4 by contracting the hole under the bright light and expanding the hole under the dark light.
An eye lens 5 is a colorless and transparent avascular structure having a convex lens shape in both sides, and arranged in the back of the iris 2. The eye lens 5 is an organ that takes part in reflecting the light entering the eye together with the cornea 1, and a shape thereof is changed according to the contraction and relaxation of a ciliaris muscle 6 and a zonule of Zinn 7 coupled to the cilaris muscle 6.
Presbyopia is a state that the hardness of the eye lens 5 increases with the age, and therefore the shape of the eye lens 5 is not changed even if the ciliaris muscle 6 contracts, and the cataract is a disease that the eye lens 5 becomes opaque with the age.
The eye lens 5 is filled inside a capsular sac 8, and the capsular sac 8 is composed of an anterior capsule 8a and a posterior capsule 8b, each of which is in contact with an anterior surface 5a and a posterior surface 5b of the eye lens 5. At this time, the anterior surface 5a and the posterior surface 5b are coupled to each other in an equator E. Each of the anterior surface 5a and the posterior surface 5b is divided into a central region a and an equatorial region b according to the distance from the equator E. The central region a of the anterior surface 5a has a lesser curvature than the central region a of the posterior surface 5b, and the equatorial region b of the anterior surface 5a has a larger curvature than the equatorial region b of the posterior surface 5b. 
The zonule of Zinn 7 is coupled along an edge of the capsular sac 8. The zonule of Zinn 7 is a fibrous tissue that couples the ciliaris muscle 6 and the capsular sac 8, and is composed of a first zonule portion 7a coupled to the center of the equatorial region in which the anterior capsule 8a and the posterior capsule 8b of the capsular sac 8 meets, and a second zonule portion 7b coupled to a circumference of the equatorial region.
FIGS. 3 and 4 are illustrative views showing an interaction of the zonule of Zinn, the eye lens, and the capsular sac when focused on a long distant and a short distance objects, respectively. In this specification, a Y-direction represents a visual axis direction of the eye lens, an X-direction represents an equatorial direction of the eye lens. The visual axis direction of the eye lens 5 means a direction that the light enters the eye lens 5 through the pupil, and the equatorial direction means a direction that, as a vertical direction of the visual axis direction, connects a point that the anterior capsule and the posterior capsule of the eye lens meets.
In the zonule of Zinn 7, the first zonule portion 7a coupled to the center of the equatorial region of the capsular sac 8 is pulled taut and the second zonule portion 7b coupled to the circumference of the equatorial region of the capsular sac 8 is relaxed when focused on the long distance object. As a result, the capsular sac 8 is extended in an X direction of the eye lens 5, and therefore the eye lens 5 arranged inside the capsular sac 8 is extended in the same direction.
In the zonule of Zinn 7, the first zonule portion 7a coupled to the center of the equatorial region of the capsular sac 8 is relaxed and the second zonule portion 7b coupled to the circumference of the equatorial region of the capsular sac 8 is pulled taut when focused on the short distance object. As a result, the capsular sac 8 as projected in a Y-direction of the eye lens and therefore eye lens 5 arranged inside the capsular sac 8 is extended in the same direction. As described above, the capsular sac 8 having a natural eye lens disposed therein is coupled to the zonule of Zinn 7, and takes part in deforming shapes of the natural eye lens actively, but when applying the conventional intraocular lens and capsular tension ring forces the capsular sac to contract, which leads the substantial loss of its functions.
In particular, the ciliaris muscle 6, which is coupled to the zonule of Zinn 7 to take part in the deformation of the eye lens 5, is intrinsic ocular muscle that maintains the endless function until a person dies. Therefore, the conventional method of artificially removing an ability of healthy ciliaris muscle 6 must be improved.
In addition, development of the intraocular lens assembly structure is needed when surgically inserting the intraocular lens, which the assembly transfers force generated by movement of the zonule of Zinn 7 to the intraocular lens effectively, thereby improving performance of the intraocular lens.